Add more tests and some reading logic

test/Microsoft.Extensions.DependencyModel.Tests/JsonAssetions.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using FluentAssertions;
+using FluentAssertions.Execution;
+using FluentAssertions.Primitives;
+using Newtonsoft.Json.Linq;
+
+namespace Microsoft.Extensions.DependencyModel.Tests
+{
+    public static class JsonAssertionExtensions
+    {
+        public static JsonAssetions Should(this JToken jToken)
+        {
+            return new JsonAssetions(jToken);
+        }
+    }
+
+    public class JsonAssetions: ReferenceTypeAssertions<JToken, JsonAssetions>
+    {
+        public JsonAssetions(JToken token)
+        {
+            Subject = token;
+        }
+
+        protected override string Context => nameof(JToken);
+
+        public AndWhichConstraint<JsonAssetions, JToken> HaveProperty(string expected)
+        {
+            var token = Subject[expected];
+            Execute.Assertion
+                .ForCondition(token != null)
+                .FailWith($"Expected {Subject} to have property '" + expected + "'");
+
+            return new AndWhichConstraint<JsonAssetions, JToken>(this, token);
+        }
+
+        public AndConstraint<JsonAssetions> NotHaveProperty(string expected)
+        {
+            var token = Subject[expected];
+            Execute.Assertion
+                .ForCondition(token == null)
+                .FailWith($"Expected {Subject} not to have property '" + expected + "'");
+
+            return new AndConstraint<JsonAssetions>(this);
+        }
+    }
+}